1. Field of the Invention
This invention relates to the properties of metals and more particularly to the properties of metal layers.
2. Art Background
The chemical and physical properties of metals, e.g., the inertness of noble metals such as gold, platinum, and palladium, have made metals useful in a variety of applications. Often, however, the use of one desirable property of a metal in a specific application is precluded by other properties of the metals or by the very property which is deemed desirable. For example, although chemical inertness makes noble metals such as gold quite useful for many applications, e.g., electrical contacts, it also significantly increases both the difficulty involved in fabricating components which include these metals and increases the difficulty involved in adapting these metals for specific uses. In particular, thin-film gold contacts are employed in many electronic components. The use and fabrication of these contacts presents the problem of depositing a continuous, adherent gold film on a desired substrate which will withstand the abrasion typically endured during use. Generally, to limit the abrasion experienced and to lengthen lifetime the contacts are lubricated. However, the inert character of the gold not only reduces adhesion of the film to the substrate but also often precludes wetting of the film by the lubricant. Thus, in this situation the property of the metal which makes it desirable also makes it difficult to use.
For each individual problem encountered in the use of metals such as noble metals, an individual procedure for reducing or eliminating this difficulty has been developed. This case-by-case approach is further necessitated by the requirement that the process employed to overcome the problem being addressed does not in turn degrade the desirable properties of the metal. In accordance with this case-by-case approach, various methods have been evolved for plating materials such as oxides or plastics with a metal film having useful electrical conductivity. (See, for example, Modern Electrochemistry, F. A. Lowenheim, Ed., John Wiley & Sons, New York, 1974.) The particular plating procedure employed significantly depends on the composition of the substrate material, on the particular metal being deposited, and the ultimate use of the deposited metal. A single unifying approach which allows the solution of a large variety of problems encountered by utilization of metals such as noble metals has not been developed.